Device for the inductive hardening of workpieces which can be rotated around a revolving axis

ABSTRACT

Apparatus for inductively hardening workpieces, such as crankshafts, which have different surface parts which are heated by different shaped inductors which partially surround the surface to be hardened. The apparatus includes means for mounting a number of workpieces for rotation and for indexing between a hardening position and a position in a quenching bath, a plurlaity of inductors mounted on an indexing spider which is in turn mounted on a plate with a transformer, that plate being moveable toward and away from the workpiece and along the workpiece axis. The indexing spider is rotateable to present different inductors according to a predetermined program and movable along its axis of rotation to couple and uncouple an inductor in a hardening position from the transformer.

CAN BE ROTATED AROUND A REVOLVING AXIS United States Patent 11 1 1111 3,927,870

Seulen et al. Dec. 23, 1975 DEVICE FOR THE INDUCTIVE 2,552,514 5/1951 Bowlus 219/1019 x HARDENING ()F WORKPIECES WHICH 2,787,566 4/1957 Seulen et al 266/4 E X 3,174,738 3/1965 Seulen et al 266/5 E Primary Examiner-Roy Lake [75] Inventors: Gerhard Seulen; Friedhelm Reinke, AssismmEmminmPau] A ll both of Remscheld; Edgar g Attorney, Agent, or Firm-Cushman, Darby & Wuppertal-Hahnerberg, all of C hman Germany [73] Assignee: AEG-Elotherm G.m.b.H., [57] v ABSTRACT Remscheld Germany Apparatus for inductively hardening workpieces, such [22] Fil d; J 26,1974 as crankshafts, which have different surface parts which are heated by different shaped inductors which [21] Appl' 483,452 partially surround the surface to be hardened. The apparatus includes means for mounting a number of [30] F i A li i p i i Data workpieces for rotation and for indexing between a July 5 1973 German 2334126 hardening position-and a position in a quenching bath, a plurlaity of inductors mounted on an indexing spider USLCLJ H 4 WhlCh IS in 'turn mounted on a plate with a trans- 1 5 2 4 former, that, plate being moveable toward and away 1 km z U (321]) 5 C21D U from the workpiece and along the workpiece axis. The [58] Field of 48/150 219/10 47 indexing spider is rotateable to present different in- 57 10 266/4 El i ductors accordingvto a predetermined program and movable along, its axis of rotation to couple and un- [56] Reerences Cited couple an inductor in a hardening position from the UNITED STATES PATENTS transfm 2,428,705 10/1947 Finger 219/1019 55cm, 2 Drawing Figures O A g -42 o jr 0 g if 20 1, {v 2 If I I0 Z/ US. Patent Dec.23, 1975 Sheet1of2 3,927,870

US. Patent Dec. 23, 1975 Sheet 2 of2 3,927,870

DEVICE FOR THE INDUCTIVE HARDENING OF WORKPIECES WHICH CAN BE ROTATED AROUND A REVOLVING AXIS The invention relates to a device for the inductive hardening of workpieces which can be rotated around a revolving axis, especially the bearing of crankshafts, in the rotary process, in which different parts'of the surface of the workpieces are heated by means of differently profiled inductors which only partially span the surface to be hardened, with a hardening carriage which can be conveyed to a parallel position to the revolving axis of the workpiece and can be locked in position in the individual operating positions, a transformer which is arranged at the hardening carriage to be vertically adjustable and swiveling over rods. The transformer is connected with a medium frequency source of current over flexible primary conductors.

A semiautomatic device which works according to this principle is known from, for example, the German Pat. No. 865,321. In its frame, this device contains a tank for receiving the quenching medium, a carrier shaft which is arranged above this tank with its axis in horizontal position. At this carriage shaft, four pairs of holders withclamping elements are each axially shifted against each other for receiving a crankshaft. This carrier shaft is connected with a gear unit, which, on one hand serves for rotating the piece by the carrier shaft which brings the crankshafts held in the clamping elements of the holders from a clamping station accessible to the operator in which the inductive hardening is carried out simultaneously gradually over three stations located in the quenching medium bath, back to the clamping station. I

A hardening carriage is provided for the inductive heating of the surface areas of the bearing surfaces. This hardening carriage can, on carrier tracks at the edge of the quenching medium tank, be driven in the direction parallel to the carrier shaft axis or to the axis of the clamped crankshafts. A medium frequency powertransformcr which is fed over flexible conductors is connected to the inductor on the secondaryside, electrically, as well as rigidly from a mechanical point of view, but can be detached. This transformer forms a unit with the inductor and is connected with the hardening carriage over its carrier plate and a double rod system alon'gthe lines of a pantograph. The weight of the transformer-inductor unit with the carrier plate together with the rods is for the most part balanced by means of balance weight so that the inductor block during the inductive heating sits with a relatively low force on the bearing to be hardened.

During the operation, four crankshafts eachare manually clamped by the operator between the four pairs of holders of the carrier shaft. Subsequently, the operator shifts the hardening carriage until the axial position of the inductor corresponds to that of the bearing to be hardened of the crankshaft located in the clamping or heating station. Then he manually places the inductor on the bearing to be hardened of the crankshaft which, in the meantime, was started into rotation. Next the inductive heating ofthebearing is initiated by turning on the inductor current. The turning-off of the inductor current is then, after the completed heating-up, carried out by means of a time switch. Then the inductor automatically lifts off, and a rotation-through-the-piece of the carrier shaft is started, thus directing the crankshaft with the just heated-up bearing into the quenching medium bath for quenching, and the next shaft into the heating position. The hardening of the corresponding bearing of the crankshaft now located in the heating station can in the same position of the hardening carriage be carried out in an analogous manner.

These steps arerepeated until the bearings corresponding to this position of the hardening carriage of all four clamped crankshafts are hardened. If the clapmed inductor can serve for the hardening of several bearings'at the crankshaft, the just described process is repeated in the positions of the hardening carriage corresponding to these bearings. The same is carried out in each case with one or several other inductors until all crankshaft bearings are hardened.

In order to increase the crankshaft throughput, a variant of the device described in the known German patent 865,321 has become known, in which two hardening tanks are arranged next to each other which each have one carrier shaft with holders for the clamping of the crankshafts and which are served by the same hardening carriage which can be driven along thetwo hardening tanks. This has the advantage that when the loading or unloading of the crankshafts takes place at one hardening tank, the other hardening tank can be used for hardening and vice versa. In the case of this socalled semiautomaticconstruction of the device, which has proven itself for' many years, one or, for a two-tank device, at least two operators are required at all times.

For the hardening of crankshafts with large throughput values per hour, independently operating devices for the inductive hardening of crankshafts are also known, for example from the German Pat. 1,209,137, in which the crankshafts are, by means of a conveying mechanism transferred in the direction vertical to their axes, in a successive manner, to two hardening stations where they are in each case clamped in, and several of their bearings are then simultaneously thrown into gear with in each case one pertaining transformer-inductor unit. During the rotating of the crankshaft, the bearings are then, byvmeans of inductors placed onthem, inductively heated, afterwhich the quenching is carried out by means of quenching sprinklers connected with these inductors. Then the crankshaft is stopped in its rotation, is released and conveyed.

This known automatically operating device for the inductive heating of crankshafts with the increased power consumption necessary for the simultaneous hardening of'several bearings, results in very high technical expenses which is only justified in the case of very large crankshaft-throughput values.

The invention is based on the task of finding a device for the, with thei'exception of the clamping and releasing process, automatic inductive hardening of surface areas of workpieces having a revolving axis, especially the bearings of crankshafts, which represents only a slightly higher expense than the mentioned known semiautomatic device, permits in each case-a simple and rapid change-over to another type of shaft and is considerably less expensive than the mentioned known automatically operating crankshaft hardening device.

In order to solve this problem in devices of the above detailed type, an older, not pre-published suggestion proposes to make the arrangement in such a way that an inductor magazine located within the driving range of the hardening carriage in which the different inductors can be placed next to each other in a direction which is parallel to the revolving axis of the workpiece. An automatically operated coupling is then provided for mounting of the inductors on the transformer plate and for making the electrical connection of the corresponding inductor with the secondary connections of the transformer; and a program device is provided for moving the hardening carriage and the transformerinductor unit into working and changing positions as well as for the startand the termination of the individual working sequences (German patent application P 23 32 832).

Starting from such devices in which the inductors can be automatically coupled with the secondary connections of the transformer and a program device is provided for the moving of the hardening carriage and the transformer-inductor unit into the working nand changing position as well as for the start and termination of the individual working sequences, the invention solves the above mentioned problem on devices of the above described type through a construction wherein the inductors are arranged next to the transformer at one level on a carrier spider which is mounted on an axis which can be rotated and is vertical to the joint inductor level and is mounted with this axis on the transformer plate. A drive is provided for the gradual rotation of the carrier spider and the connections for the inductor cooling medium can be automatically coupled to the corresponding connections of the respective inductor which is in the working position.

This arrangement has the advantage that even in the case of a relatively small number of necessary inductors the task on which the invention is based, is solved with relatively simple means.

In an advantageous construction, in the device according to the invention the inductor spider is connected to a shaft which is pivoted on the transformer support (transformer plate) and the drive coupled with the shaft is, for partially rotating the inductor spider, connected with a setting mechanism for axially shifting the inductor spider to couple and uncouple the connections. It is advantageous for the setting mechanism to have, for the coupling of the connections, an accumulator pressing the connections against each other, preferably a pressure spring, and for their uncoupling an adjusting cylinder which shifts the inductor spider against the effect of the accumulator.

In the following, the invention is further described by means of drawings. In a schematic perspective partial diagram, FIG. 1 shows the parts required for an automatically operating crankshaft hardening device, with the exception of the charging and discharging process, which are essential for the object of the invention. In a partial diagram, FIG. 2 shows details of the machine according to FIG. 1. Referring to the Figures, frame 1 of the device contains a hardening tank 2, in which a carrier shaft 4 is located with a horizontal axis. The four pairs of holders of this carrier shaft 4 (two of them are visible in FIG. 1) clamp, by means of spindle sleeves 6, crankshaft 7 between points. To avoid confusion, FIG. 1 shows crankshaft 7 of the crankshafts to be received by the carrier shaft 4 which, at the time, is in the heating position outside the quenching medium bath. For rotating crankshaft 7, as well as the spindle sleeves 6, a conventional gear unit 8 is used. At the rear edge of the tank, the device also has a ramp with tracks 9 on which driven by means of a geared engine 10 over a spindle 11 a hardening carriage 12 can be driven in the direction parallel to the clamping axis of the crankshaft between several axial positions. A slid= ing carriage 13 is mounted, vertically shiftable on the hardening carriage 12, on which, over a swinging deflectable parallelogram rod system 14, a transformer support 15 can be swivelled to a level, the normal line of which in parallel to the clamping axis of the crankshaft. The transformer support 15 carries a medium frequency power transformer 16 which, on the primary side, over flexible conductors (not shown in FIG. 1) is connected with the condenser battery of a medium frequency generator located in the hardening carriage 12. An inductor spider 17 with several different half shell inductors 18 is pivoted on the transformer support 15, in which case each of these inductors 18 can be brought into a working position, in which its center line has a vertical position as shown in FIG. 2.

FIG. 2 shows a partial section of the structure suspended on the parallelogram rod system 14 which includes the transformer support 15 and the inductor spider 17. The transformer support 15 on which the rods 14 of the parallelogram rod system are pivoted in bearing 19, has a bushing 20 in which a shaft 21 is pivotably mounted. At the end of the shaft 21 secured against rotation the induction spider 17 is slid on, while the other end of the shaft is coupled with a gear unit 22 which is screwed on at the bushing 20. This gear 22 which together with a motor 23 forms a driving aggregate to rotate inductor spider 17. An axially shiftable adjusting rod 24 is arranged in the hollow shaft 21. This adjusting rod 24 is, on one end connected with the inductor spider 17 (not shown) and on the other end of the shaft with a pressure spring 25, which can be compressed by means of an adjusting cylinder 26. The secondary transformer connections or the inductor cooling medium connections 27 are each coupled with the corresponding connections 28 0f the inductor which is in working position.

The device described by means of FIGS. 1 and 2, works as follows. It is assumed that the hardening carriage is in the position shown in FIG. 1 with the sliding carriage 13 in its highest position. It is also assumed that in this phase of the working sequence, for example, the hardening of all hearings to be hardened by means of the coupled inductor 18 is concluded. This condition now triggers a starting signal for the change of the inductor or the moving of the hardening carriage l2 intoits first axial hardening position to the next inductor.

The changing of the inductor is now carried out in such a way that at first, through the activation of the adjusting cylinder 26, the adjusting rod 24 and with it the inductor spider is axially shifted against the force of the pressure spring (to the left in FIG. 2) thus releasing the secondary transformer connections or the inductor cooling medium connection 27 from the corresponding connections 28 of the inductor to be changed. Subsequently, by means of the drive 22 and 23, one or more rotary movements through the piece of the inductor spider 17 are made until the inductor programmed to beconnected next to the inductor spider with its connections 28 is located opposite the corresponding connections 27 at the transformer support 15. Finally, after the ventilation of the adjusting cylinder 25, the inductor spider 17 is, through the effect of the pressure spring 26 pressed against the connections 27, thus making the electrical or cooling medium connection of the inductor now just brought into working position and the change of the inductor is thus completed.

After the inductor has been changed, the automatic hardening process is then triggered on all crankshaft bearings pertaining to this newly connected inductor.

For each axial position of the hardening carriage 12 to be taken at this inductor for the purpose of harden ing, this hardening process consists of four successive hardening processes in which case the termination of the hardening process triggers the start of the next one, and the end of the last, fourth, hardening process causes the moving of the hardening carriage 12 into its next axial position pertaining to the coupled inductor, in which the four pertaining hardening processes are then triggered again, etc. until all bearings pertaining to the clamped-in inductor are hardened and the next inductor changing process is carried out automatically. This is continued until all bearings of the clamped-in shafts are hardened and the process is stopped for charging with new crankshafts.

Each of the mentioned hardening processes consists of the placing of the inductor on the bearing to be hardened by lowering the sliding carriage l3 and the separation of the carriage from its lifting device (as it is known, for example from the German Pat. No. 1,209,137 for automatic crankshaft hardening devices), the start of the rotary movement of the shaft and the turning-on of the inductor current, the turning-off of the inductor current by means of a time switch, the driving-up of the sliding carriage l3 and finally the rotation through the piece of the carrier shaft 4, by which the crankshaft with the just inductively heated bearing is lowered into the quenching medium bath and another shaft is brought into the heating position. The termination of the hardening process then starts the new hardening process with the lowering of the sliding carriage 13 or rather the placing of the inductor on the bearing now to be hardened of the next crankshaft which is held in an azimuthally indicated position.

In a preferred construction, described in FIG. 1, the device may be equipped with two hardening tanks instead of with one as mentioned as known in the introduction of the description. Each of the two hardening tanks has a carrier shaft with holders for the clamping-in of the crankshafts. In such a modification of the device, when the charging or discharging takes place at one hardening tank, the hardening can be carried out at the other tank and vice versa, and thus, an increased crankshaft throughput is achieved.

For the control of the automatic operating sequence in the case of the described devices, known control elements, like limit and approach switches are used which, in the case of an indicated adjustment of a part of the device, or time switches which, for example during the turning-on period of the inductor switch, cause the termination of the corresponding work phase of the device and simultaneously emit a signal for the start of the working phase of the device which is programmed to be next. In particular, a cam ledge with cams that can be adjusted along the hardening course, is for example provided for the stopping of the hardening carriage in its operating or inductor changing positions. These cams activate a limit switch mounted on the hardening carriage. A change-over of the device to another type of crankshaft can be carried out by a corresponding new line-up of the inductor magazine with the inductors pertaining to the new type of crankshaft, a corresponding pre-adjustment of the heating time, the heating capacity and the compensation condensers for each inductor as well as a new adjustment of the cams of the mentioned cam ledge.

Deviating from the described devices which all work automatically with the exception of the clamping-in and clamping-out process of the workpiece, the device according to the invention can also be equipped with automatically operating devices for the input of the workpieces, for the clamping-in and clamping-out and for the removal of the workpieces, as it is known, for example, from the device described in German Pat. No. 1,209,137. In this case, the inductors are combined with quenching sprinklers, and the quenching takes place in the heating-up position of the workpiece. The operation of such a device is then fully automatic, i.e. the hardening process including the charging and discharging processes of the machine is carried out automatically.

What is claimed is:

1. An apparatus for inductively hardening workpieces of the type in which different parts of the surface are heated by different shaped inductors which partially surround the surface to be hardened comprising:

means for mounting a plurality of said workpieces for axial rotation and for indexing movement between a plurality of treating positions including a hardening position,

a plurality of different shaped inductors,

a carrier spider mounting said inductors for presenting one of said inductors to a workpiece mounted in said hardening position,

a transformer,

means for removably coupling said inductor in said hardening position to said transformer,

means for rotating said carrier spider about a given axis to sequentially present each of said inductors to a workpiece, and

means for moving said carrier spider along said given axis to uncouple said inductor from said transformer.

2. An apparatus as in claim 1 further including plate means for mounting said moving means, coupling means, rotating means and carrier spider and linkage means for moving said plate toward and away from a workpiece in said hardening position.

3. An apparatus as in claim 2 further including means for moving said plate along the axis of said workpiece.

4. An apparatus as in claim 1 further including a quenching bath. j

5. An apparatus as in claim 1 wherein said rotating means includes a hollow shaft and said moving means includes a rod movable in said hollow shaft and engaging said spider and a spring engaging said rod to urge said shaft and spider into a position in which an inductoris coupled to said transformer. 

1. An apparatus for inductively hardening workpieces of the type in which different parts of the surface are heated by different shaped inductors which partially surround the surface to be hardened comprising: means for mounting a plurality of said workpieces for axial rotation and for indexing movement between a plurality of treating positions including a hardening position, a plurality of different shaped inductors, a carrier spider mounting said inductors for presenting one of said inductors to a workpiece mounted in said hardening position, a transformer, means for removably coupling said inductor in said hardening position to said transformer, means for rotating said carrier spider about a given axis to sequentially present each of said inductors to a workpiece, and means for moving said carrier spider along said given axis to uncouple said inductor from said transformer.
 2. An apparatus as in claim 1 further including plate means for mounting said moving means, coupling means, rotating means and carrier spider and linkage means for moving said plate toward and away from a workpiece in said hardening position.
 3. An apparatus as in claim 2 further including means for moving said plate along the axis of said workpiece.
 4. An apparatus as in claim 1 further including a quenching bath.
 5. An apparatus as in claim 1 wherein said rotating means includes a hollow shaft and said moving means includes a rod movable in said hollow shaft and engaging said spider and a spring engaging said rod to urge said shaft and spider into a position in which an inductor is coupled to said transformer. 